Semiconductor wetdeck processes are employed during the manufacture of semiconductor wafers. There are various types of semiconductor wetdeck processes (e.g., diffusion, wet etch, resist strip, bath develop, etc.). Consider a diffusion wetdeck process as an exemplary semiconductor wetdeck process. A diffusion wetdeck process comprises at least one chemical bath for cleaning the semiconductor wafers. A chemical bath generally comprises a chemical bath liquid within a chemical bath container. The semiconductor wafers are placed in the chemical bath and the chemicals in the chemical bath treat the semiconductor wafers. For example, semiconductor wafers may be subjected to chemicals to clean organic contaminants from the surface of the semiconductor wafers.
As the semiconductor wafers are treated the process chemicals are consumed. The process chemicals may break down, evaporate, or combine with other chemicals. As time goes by the effectiveness of the chemical process decreases. Eventually the effectiveness of the chemicals in the chemical bath is spent.
When the chemicals in a chemical bath are no longer effective, the chemical bath container is totally drained and replaced with new chemicals. The provision of a new chemical bath is referred to as a “solution change.” The “solution change” occurs at a prescribed frequency. The frequency of “solution change” may be based on time, on chemical bath usage, or on some measurement of chemical bath performance. There is an unavoidable period of “down” time while the “solution change” process is being performed. In addition, the provision of new chemicals for the chemical bath incurs additional cost.
Therefore, there is a need in the art for a system and method that is capable of extending the effective working life of a chemical bath in a semiconductor wetdeck process.